Toward accurate models of intermediate-mass-ratio gravitational waves: combining numerical relativity and black-hole perturbation theory
Accurate gravitational-wave models for intermediate-mass-ratio binaries remain a major challenge: numerical relativity (NR) is prohibitively expensive in this regime, while point-particle black-hole perturbation theory (ppBHPT) neglects important nonlinear effects. In this talk, we present a modeling framework that bridges these approaches. Beginning with inspiral–merger–ringdown ppBHPT waveforms, we introduce simple calibration parameters fixed both by comparison to NR simulations and by enforcing the correct behavior in the extreme-mass-ratio limit. This prescription yields spin-aligned waveform models that maintain good accuracy across comparable to large mass ratios. As a byproduct, we also find that ppBHPT spin effects - captured without corrections beyond adiabatic order - can reasonably model NR waveform frequency, amplitude, and orbital phasing. Looking ahead, we outline ongoing efforts to incorporate more physics into perturbation-theory-based models, such precessing systems, as a step toward robust intermediate-mass-ratio waveform modeling.